I've sussed it! I found that you can "teleport" left / right purely by accident (can't find any reference to this anywhere). Whilst holding up, quickly press the left or right key (depending on which way you want to teleport) and this allows to get across those pesky spike traps with ease.

As for the screenshot above. I had to go to the screen to the left of this and get onto the platform that is level with the amulet part and teleport myself across!

Hmmmm..... apparently there are still TWO amulet parts I need to find! Nor these show up on the map either (had already bought the additional map for 300c). I've got to a altar which informs me that I need all amulet parts! Damn..... where could they be?